Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

Pull gcc "asm goto" miscompilation workaround from Ingo Molnar:
 "This is the fix for the GCC miscompilation discussed in the following
  lkml thread:

    [x86] BUG: unable to handle kernel paging request at 00740060

  The bug in GCC has been fixed by Jakub and the fix will be part of the
  GCC 4.8.2 release expected to be released next week - so the quirk's
  version test checks for <= 4.8.1.

  The quirk is only added to compiler-gcc4.h and not to the higher level
  compiler.h because all asm goto uses are behind a feature check"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  compiler/gcc4: Add quirk for 'asm goto' miscompilation bug

diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
index bfc198c759130109d44b73b4506ea853d01fba28..863c892b4aaa7403c3bde97b7de3b2cd9a75519c 100644 (file)
--- a/arch/arm/include/asm/jump_label.h
+++ b/arch/arm/include/asm/jump_label.h
@@ -16,7 +16,7 @@
 
 static __always_inline bool arch_static_branch(struct static_key *key)
 {
-       asm goto("1:\n\t"
+       asm_volatile_goto("1:\n\t"
                 JUMP_LABEL_NOP "\n\t"
                 ".pushsection __jump_table,  \"aw\"\n\t"
                 ".word 1b, %l[l_yes], %c0\n\t"

diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
index 4d6d77ed9b9d679cd955e2fafe2dbc16527db65c..e194f957ca8c42a0af82f0621c425308a25e4d53 100644 (file)
--- a/arch/mips/include/asm/jump_label.h
+++ b/arch/mips/include/asm/jump_label.h
@@ -22,7 +22,7 @@
 
 static __always_inline bool arch_static_branch(struct static_key *key)
 {
-       asm goto("1:\tnop\n\t"
+       asm_volatile_goto("1:\tnop\n\t"
                "nop\n\t"
                ".pushsection __jump_table,  \"aw\"\n\t"
                WORD_INSN " 1b, %l[l_yes], %0\n\t"

diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
index ae098c438f009eb0e312fc8b78a6ce07f4311cc6..f016bb699b5f6200268d3b8e5bf4e2bd003dbbf7 100644 (file)
--- a/arch/powerpc/include/asm/jump_label.h
+++ b/arch/powerpc/include/asm/jump_label.h
@@ -19,7 +19,7 @@
 
 static __always_inline bool arch_static_branch(struct static_key *key)
 {
-       asm goto("1:\n\t"
+       asm_volatile_goto("1:\n\t"
                 "nop\n\t"
                 ".pushsection __jump_table,  \"aw\"\n\t"
                 JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"

diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
index 6c32190dc73e880255175049fe36965e647101eb..346b1c85ffb40d890078550dc72c2dedcb275a2e 100644 (file)
--- a/arch/s390/include/asm/jump_label.h
+++ b/arch/s390/include/asm/jump_label.h
@@ -15,7 +15,7 @@
 
 static __always_inline bool arch_static_branch(struct static_key *key)
 {
-       asm goto("0:    brcl 0,0\n"
+       asm_volatile_goto("0:   brcl 0,0\n"
                ".pushsection __jump_table, \"aw\"\n"
                ASM_ALIGN "\n"
                ASM_PTR " 0b, %l[label], %0\n"

diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h
index 5080d16a832ffec0c813b30cf546340e5047a7fd..ec2e2e2aba7d8f15419aa12bc6f790993f8c54d4 100644 (file)
--- a/arch/sparc/include/asm/jump_label.h
+++ b/arch/sparc/include/asm/jump_label.h
@@ -9,7 +9,7 @@
 
 static __always_inline bool arch_static_branch(struct static_key *key)
 {
-               asm goto("1:\n\t"
+               asm_volatile_goto("1:\n\t"
                         "nop\n\t"
                         "nop\n\t"
                         ".pushsection __jump_table,  \"aw\"\n\t"

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index d3f5c63078d812e2f6220cfa5ad322aae920827c..89270b4318db8b97ac467717b38863fa549435ad 100644 (file)
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -374,7 +374,7 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
                 * Catch too early usage of this before alternatives
                 * have run.
                 */
-               asm goto("1: jmp %l[t_warn]\n"
+               asm_volatile_goto("1: jmp %l[t_warn]\n"
                         "2:\n"
                         ".section .altinstructions,\"a\"\n"
                         " .long 1b - .\n"
@@ -388,7 +388,7 @@ static __always_inline __pure bool __static_cpu_has(u16 bit)
 
 #endif
 
-               asm goto("1: jmp %l[t_no]\n"
+               asm_volatile_goto("1: jmp %l[t_no]\n"
                         "2:\n"
                         ".section .altinstructions,\"a\"\n"
                         " .long 1b - .\n"
@@ -453,7 +453,7 @@ static __always_inline __pure bool _static_cpu_has_safe(u16 bit)
  * have. Thus, we force the jump to the widest, 4-byte, signed relative
  * offset even though the last would often fit in less bytes.
  */
-               asm goto("1: .byte 0xe9\n .long %l[t_dynamic] - 2f\n"
+               asm_volatile_goto("1: .byte 0xe9\n .long %l[t_dynamic] - 2f\n"
                         "2:\n"
                         ".section .altinstructions,\"a\"\n"
                         " .long 1b - .\n"              /* src offset */

diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 64507f35800ce23e9c867e1c80b5dc3d0a835ec1..6a2cefb4395a4228cce550ef8b231f3e7158d9d1 100644 (file)
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -18,7 +18,7 @@
 
 static __always_inline bool arch_static_branch(struct static_key *key)
 {
-       asm goto("1:"
+       asm_volatile_goto("1:"
                ".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
                ".pushsection __jump_table,  \"aw\" \n\t"
                _ASM_ALIGN "\n\t"

diff --git a/arch/x86/include/asm/mutex_64.h b/arch/x86/include/asm/mutex_64.h
index e7e6751648edf775ad54a42a5c05b3e6d3c1cff5..07537a44216ec9b2eed302183af7c57d8949a5a0 100644 (file)
--- a/arch/x86/include/asm/mutex_64.h
+++ b/arch/x86/include/asm/mutex_64.h
@@ -20,7 +20,7 @@
 static inline void __mutex_fastpath_lock(atomic_t *v,
                                         void (*fail_fn)(atomic_t *))
 {
-       asm volatile goto(LOCK_PREFIX "   decl %0\n"
+       asm_volatile_goto(LOCK_PREFIX "   decl %0\n"
                          "   jns %l[exit]\n"
                          : : "m" (v->counter)
                          : "memory", "cc"
@@ -75,7 +75,7 @@ static inline int __mutex_fastpath_lock_retval(atomic_t *count)
 static inline void __mutex_fastpath_unlock(atomic_t *v,
                                           void (*fail_fn)(atomic_t *))
 {
-       asm volatile goto(LOCK_PREFIX "   incl %0\n"
+       asm_volatile_goto(LOCK_PREFIX "   incl %0\n"
                          "   jg %l[exit]\n"
                          : : "m" (v->counter)
                          : "memory", "cc"

diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h
index 842de225055fc5b8c769c59ff37e5afa81574f38..ded429966c1f447db9106359b174fb742fd3fe54 100644 (file)
--- a/include/linux/compiler-gcc4.h
+++ b/include/linux/compiler-gcc4.h
@@ -65,6 +65,21 @@
 #define __visible __attribute__((externally_visible))
 #endif
 
+/*
+ * GCC 'asm goto' miscompiles certain code sequences:
+ *
+ *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
+ *
+ * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
+ * Fixed in GCC 4.8.2 and later versions.
+ *
+ * (asm goto is automatically volatile - the naming reflects this.)
+ */
+#if GCC_VERSION <= 40801
+# define asm_volatile_goto(x...)       do { asm goto(x); asm (""); } while (0)
+#else
+# define asm_volatile_goto(x...)       do { asm goto(x); } while (0)
+#endif
 
 #ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
 #if GCC_VERSION >= 40400